diff --git a/scripts/sendGraph.py b/scripts/sendGraph.py
index 2805684..87558f8 100755
--- a/scripts/sendGraph.py
+++ b/scripts/sendGraph.py
@@ -48,7 +48,7 @@ def main():
 	all_edges = []
 
 	for process in range(0, 1 if cjdns_use_default else cjdns_processes):
-		print "Connecting port %d..." % (cjdns_first_port + process),; sys.stdout.flush()
+		print 'Connecting port %d...' % (cjdns_first_port + process),; sys.stdout.flush()
 
 		try:
 			cjdns = cjdns_connect(process)
@@ -62,7 +62,7 @@ def main():
 				if not e in all_edges:
 					all_edges.append(e)
 		except Exception, err:
-			print "Failed!"
+			print 'Failed!'
 			print traceback.format_exc()
 
 	success = send_graph(all_nodes, all_edges)
@@ -71,10 +71,10 @@ def main():
 
 def generate_graph(cjdns):
 	source_nodes = cjdns_get_node_store(cjdns)
-	print "  Found %d source nodes." % len(source_nodes)
+	print '  Found %d source nodes.' % len(source_nodes)
 
 	nodes, edges = cjdns_graph_from_nodes(cjdns, source_nodes)
-	print "  Found %d nodes and %d links." % (len(nodes), len(edges))
+	print '  Found %d nodes and %d links.' % (len(nodes), len(edges))
 
 	return (nodes, edges)
 
@@ -98,9 +98,10 @@ def send_graph(nodes, edges):
 
 	json_str = json.dumps(graph_data)
 
-	print "Sending data...",; sys.stdout.flush()
-	success = send_data(json_str)
-	print ("Done!" if success else "Failed!")
+	print 'Sending data...',; sys.stdout.flush()
+	answer = send_data(json_str)
+	success = answer == 'OK'
+	print ('Done!' if success else answer)
 
 	return success
 
@@ -207,10 +208,9 @@ def send_data(graph_data):
 	post_data = urllib.urlencode({'data': graph_data})
 	req = urllib2.Request(url, post_data)
 	response = urllib2.urlopen(req)
-	output = response.read()
-	return output == 'OK'
+	return response.read()
 
 
 
-if __name__ == "__main__":
+if __name__ == '__main__':
 	main()
diff --git a/web/graph.py b/web/graph.py
index 4a0cd4c..6c0b012 100644
--- a/web/graph.py
+++ b/web/graph.py
@@ -1,7 +1,15 @@
+import re
+
+
 class Node:
 	def __init__(self, ip, version=None, label=None):
+		if not valid_cjdns_ip(ip):
+			raise ValueError('Invalid IP address')
+		if not valid_version(version):
+			raise ValueError('Invalid version')
+
 		self.ip = ip
-		self.version = version
+		self.version = int(version)
 		self.label = ip[-4:] if label == None else label
 
 	def __lt__(self, b):
@@ -24,3 +32,18 @@ class Edge:
 		return 'Edge(a.ip="%s", b.ip="%s")' % (
 			self.a.ip,
 			self.b.ip)
+
+
+
+_re_cjdns_ip = re.compile(r'^fc[0-9a-f]{2}(:[0-9a-f]{4}){7}$', re.IGNORECASE)
+
+def valid_cjdns_ip(ip):
+	return _re_cjdns_ip.match(ip) != None
+
+def valid_version(version):
+	try:
+		return int(version) < 20
+	except ValueError:
+		return False
+
+		
\ No newline at end of file
diff --git a/web/graphData.py b/web/graphData.py
index 28c3dc0..841bc20 100644
--- a/web/graphData.py
+++ b/web/graphData.py
@@ -6,30 +6,37 @@ def insert_graph_data(config, json_str):
 	try:
 		graph_data = json.loads(json_str)
 	except ValueError:
-		return False
+		return 'Invalid JSON'
 
 	nodes = dict()
 	edges = []
 
-	if not 'nodes' in graph_data or not 'edges' in graph_data:
-		return False
-	
-
 	try:
 		for n in graph_data['nodes']:
-			node = Node(n['ip'], version=n['version'])
-			nodes[n['ip']] = node
+			try:
+				node = Node(n['ip'], version=n['version'])
+				nodes[n['ip']] = node
+			except Exception:
+				pass
 
 		for e in graph_data['edges']:
-			edge = Edge(nodes[e['a']], nodes[e['b']])
-			edges.append(edge)
+			try:
+				edge = Edge(nodes[e['a']], nodes[e['b']])
+				edges.append(edge)
+			except Exception:
+				pass
+	except Exception:
+		return 'Invalid JSON nodes'
 
-	except TypeError:
-		return False
+	print "Accepted %d nodes and %d links." % (len(nodes), len(edges))
 
-	print "Received %d nodes and %d links." % (len(nodes), len(edges))
+	if len(nodes) == 0 or len(edges) == 0:
+		return 'No valid nodes or edges'
 
-	with NodeDB(config) as db:
-		db.insert_graph(nodes, edges)
+	try:
+		with NodeDB(config) as db:
+			db.insert_graph(nodes, edges)
+	except Exception:
+		return 'Database failure'
 
-	return True
+	return None
diff --git a/web/updateGraph.py b/web/updateGraph.py
index b06d679..50daaaf 100755
--- a/web/updateGraph.py
+++ b/web/updateGraph.py
@@ -6,6 +6,7 @@ import graphPlotter
 
 def generate_graph(time_limit=60*60*3):
 	nodes, edges = load_graph_from_db(time_limit)
+	print '%d nodes, %d edges' % (len(nodes), len(edges))
 
 	graph = graphPlotter.position_nodes(nodes, edges)
 	json = graphPlotter.get_graph_json(graph)
diff --git a/web/web.py b/web/web.py
index 33a4f99..25866d2 100644
--- a/web/web.py
+++ b/web/web.py
@@ -25,10 +25,10 @@ def page_sendGraph():
 	
 	data = request.form['data']
 	ret = insert_graph_data(app.config, data)
-	if ret:
+	if ret == None:
 		return 'OK'
 	else:
-		return 'FAIL'
+		return 'Error: %s' % ret
 
 if __name__ == '__main__':
 	app.run(host='::')